A noise suppression device that suppresses noise after converting input signals in(t) into a frequency domain signal, inversely converts the frequency domain signal into a time domain signal, and outputs the signal out (t) is known.
Such noise suppression devices are installed in devices of many types such as mobile phones. In recent years, devices that include a noise suppression device each include multiple microphones for collecting sounds, and distances between microphones included in each device tend to be larger.
As a conventional noise suppression method, a method (beam forming) using an amplitude ratio is known (refer to, for example, Japanese Laid-open Patent Publication No. 2014-137414). However, when a distance between microphones is large, the sensitivities of the microphones are not equal due to the positions of the installed microphones and vocal tract shapes. When microphones that have sensitivities between which the difference is large are used and noise suppression is executed using an amplitude ratio, a target sound (voice) is largely distorted.